JPH05324011A - Pid controller - Google Patents

Abstract

PURPOSE:To reduce the degree that an overshoot or undershoot is caused as to all kind of controlled systems, to lighten the burden on an operator and shorten an adjustment time, and to perform stable control which is short in arithmetic time even if a PID constant is not adjusted so strictly. CONSTITUTION:A PID arithmetic means 1 performs the PID operation of the deviation of a measured value PV from a controlled system from a previously set value SV and outputs a manipulated variable mv corresponding to the result of the PID arithmetic to a manipulated variable correction output means 3. A fuzzy arithmetic means 2 operates a corrected manipulated variable hv for the value of the deviation of the measured value PV from the controlled system according to a membership function wherein the upper and lower limit values of the value of the deviation are fixed according to a predetermined fuzzy rule, and outputs the corrected manipulated variable hv to the manipulated variable correction output means 3. The manipulated variable correction output means 3 corrects the manipulated variable mv obtained by the PID arithmetic means 1 according to the corrected manipulated variable hv and outputs a final manipulated variable MV as a control signal of the controlled system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a controller for controlling phenomena such as temperature, humidity and pressure in an electric furnace according to a preset program pattern. The present invention relates to a PID control device that corrects parameters and outputs a manipulated variable.

[0002]

2. Description of the Related Art For example, when various heat treatments such as an electric furnace are to be controlled, a fixed value or program controller is often used. In this controller, for example, as shown in FIG. 10, constant value or trapezoidal control is performed according to a preset program pattern. More specifically, the deviation obtained by comparing the measured value PV from the thermocouple or the like arranged in the electric furnace with the set value SV according to the preset program pattern is PID-calculated, and the output after the PID-calculated is calculated. The temperature in the electric furnace based on the manipulated variable MV
It controlled the phenomena such as humidity and pressure.

[0003]

By the way, in this type of controller, PID calculation is performed so that the measured value PV converges to the set value SV and the deviation is eliminated, and each phenomenon in the electric furnace is controlled. However, in actuality, it takes time for the measured value PV to converge to the set value SV and stabilize due to the influence of the disturbance.
The control error of the overshoot OS or the undershoot US as shown in 0 occurred, and the control became unstable. Further, the control error due to the overshoot OS or the undershoot US is the most disliked in the control of this type of controller, and there is a problem that a large amount of wasted energy is consumed by this error.

Further, since each parameter of the PID constant changes depending on the control target, the operator must change the PID constant each time.
Each parameter of the PID constant in the controller was adjusted. However, since the degree of occurrence of the overshoot OS or the undershoot US is determined by the adjustment, accurate adjustment is always required and adjustment time is required, which is a work burden on the operator.

Therefore, the present invention has been made in view of the above-mentioned problems, and an object thereof is to reduce the degree of occurrence of overshoot or undershoot with respect to any controlled object and reduce the burden on the operator. Therefore, the adjustment time can be shortened, and even if the adjustment of the PID constant is not so strict, the calculation time is fast and stable control can be performed.
It is to provide an ID control device.

[0006]

In order to achieve the above object, a PID control device according to a first aspect of the present invention uses a deviation P between a preset set value and a measured value from a controlled object.
In a PID control device that calculates an ID and outputs a manipulated variable corresponding to the PID-calculated value, an upper and lower limit value of at least one of the magnitude of the deviation and the change rate of the deviation is fixed according to a predetermined fuzzy rule. Fuzzy calculation means for calculating the correction operation amount from the magnitude of the deviation of the measured value from the controlled object or the rate of change of the deviation based on the membership function, and the correction operation amount calculated by the fuzzy operation means. And a manipulated variable correction output unit that corrects the PID-calculated value based on the output and outputs a manipulated variable.

Further, a PID control device according to a second aspect performs a PID calculation of a deviation between a preset set value and a measured value from a controlled object, and outputs an operation amount corresponding to the PID calculated value. In a PID control device, the deviation of the measured value from the controlled object is based on a membership function in which the upper and lower limit values of at least one of the magnitude of the deviation and the rate of change of the deviation are variable according to a predetermined fuzzy rule. The fuzzy computing means for computing the correction operation amount from the magnitude of the deviation or the rate of change of the deviation, and the selection means for sequentially switching and selecting the fuzzy computing means according to the magnitude of the deviation or the rate of change of the deviation. A manipulated variable correction output for correcting the value calculated by the PID based on the corrected manipulated variable calculated by the fuzzy calculating unit selected by the selecting unit and outputting the manipulated amount. It is characterized in that a stage.

[0008]

The PID calculating means 1 in the invention of claim 1 is
The preset value SV and the measured value P from the controlled object
The deviation E from V is calculated by PID, and the manipulated variable mv corresponding to the result of this PID calculation is output to the manipulated variable correction output means 3. The fuzzy calculation means 2 measures the magnitude of the deviation E or the change rate Δ of the deviation E according to a predetermined fuzzy rule.
At least one of the upper and lower limit values EU, ED (or Δ
The correction operation amount hv is calculated from the magnitude of the deviation E of the measured value PV from the controlled object or the change rate ΔE of the deviation E based on the membership function in which EU, ΔED) is fixed,
This corrected manipulated variable hv is output to the manipulated variable correction output means 3. The manipulated variable correction output means 3 corrects the manipulated variable mv by the PID computing means 1 based on the corrected manipulated variable hv and outputs the final manipulated variable MV as a control signal for the controlled object.

According to the second aspect of the present invention, the membership function of the plurality of fuzzy calculation means 2 is the magnitude of the deviation E or the deviation E according to a predetermined fuzzy rule.
Upper and lower limit values EU, ED of at least one of the rate of change ΔE of
(Or .DELTA.EU, .DELTA.ED) is variable, and the fuzzy computing means 2 is sequentially switched and selected according to the magnitude of the deviation E or the rate of change .DELTA.E of the deviation E. Then, the correction operation amount h is selected by the selected fuzzy calculation means 2.
v is calculated, and the manipulated variable correction output means 3 corrects the manipulated variable mv by PID calculation based on the corrected manipulated variable hv, and outputs the final manipulated variable MV as a control signal of the control target.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a first PID controller according to the present invention.
It is a block diagram showing an example. The PID control device according to each embodiment described below is applied to, for example, a controller that controls phenomena such as temperature, humidity, and pressure in an electric furnace as a control target, and performs PID calculation when controlling each phenomenon. The manipulated variable obtained by is corrected.

First, in the PID control device of the first embodiment,
It is configured to include an ID calculation means 1, a fuzzy calculation means 2A (2), and an operation amount correction output means 3. The PID calculation means 1 receives a measured value PV from, for example, a thermocouple arranged in an electric furnace as a control target, and a preset value SV of a preset program pattern, for example. A deviation E (= SV-PV) from the value SV is calculated, and an operation amount (e.g., equivalent to electric power for driving a heater in the electric furnace) mv based on the deviation E is output to the operation amount correction output means 3. ing.

The fuzzy calculating means 2A is a PID calculating means 1
And the measured value P, which is provided in parallel with the PID calculation means 1.
V and the set value SV are input. When the deviation E occurs between the measured value PV and the set value SV, the fuzzy calculation means 2A determines the upper and lower limit values EU and ED of the deviation E to be ED =, for example, according to a predetermined fuzzy rule described later.
Based on the membership function fixed to −10 to EU = + 10, the corrected manipulated variable hv is calculated from the state of the deviation E and is output to the manipulated variable correction output means 3.

The operation amount correction output means 3 is composed of, for example, an adder or the like, and corrects the operation amount mv by adding the operation amount mv from the PID operation means 1 and the corrected operation amount hv calculated by the fuzzy operation means 2A. Then, the final manipulated variable MV corresponding to this added value is output as a control signal (for example, a heater drive signal) for the control target.

When the deviation E between the measured value PV and the set value SV does not occur in the manipulated variable correction output means 3,
The manipulated variable mv input from the PID calculation means 1 is output as it is as the final manipulated variable MV.

Next, the operation of the PID control device configured as described above will be described with reference to FIG. As an example of the fuzzy rule, (1) If the deviation E is positive, the operation amount is increased. (2) If the deviation E is zero, the manipulated variable is maintained as it is. (3) If the deviation E is negative, decrease the operation amount. It is assumed that a deviation E = + 3 is generated between the measured value PV and the set value SV input to the PID calculation means 1 by applying the three rules.

Then, the fuzzy calculation means 2A first obtains the degree of coincidence of each rule. That is, in the rule (1), since the deviation is +3, the degree W is 0.6 from the membership function A1 (see FIG. 2A). Next, in the rule (2), since the deviation is +3, the degree W is 0.4 from the membership function A2 (FIG. 2 (b)).
reference). Further, in rule (3), the deviation is +3, so the degree W is 0 from the membership function A3 (see FIG. 2 (c)).

Here, each rule (1), (2), (3)
When the degree obtained in the conclusion part is applied, the membership functions in the conclusion part become the membership functions B1, B2, B3 cut by the degree W. Next, each rule (1), (2), (3) of the conclusion part cut by the degree W
The membership functions B1, B2 and B3 of 1 are combined into one as shown in FIG. 2D, and the center of gravity of the area of the enclosed boundary portion is obtained.

Then, the obtained center of gravity is lowered vertically toward the operation amount axis (X axis), and the intersection with the operation amount axis becomes the corrected operation amount hv (= + 1.5). This corrected manipulated variable hv is added to the manipulated variable mv calculated by the PID computing means 1 in the manipulated variable correction output means 3 to correct the manipulated variable mv, and then output to the control target as the final manipulated variable MV. To be done.

Next, FIG. 3 shows a second embodiment of the PID control device, and the same components as those in the first embodiment are designated by the same reference numerals. The PID controller according to this embodiment is
When the rate of change ΔE of the deviation E between the measured value PV and the set value SV changes, the fuzzy calculation means 2B (2) causes the upper and lower limit value ΔEU of the rate of change ΔE of the deviation E according to a predetermined fuzzy rule described later. , ΔED is, for example, ΔED = −8
Based on the fixed membership function of ΔEU = + 12, the corrected manipulated variable hv is calculated from the change rate ΔE of the deviation E,
The operation amount correction output means 3 adds the operation amount mv from the PID calculation means 1 and the corrected operation amount hv to correct the operation amount mv, and the final operation amount MV corresponding to the added value is controlled as a control target. It is output as a signal (for example, a heater drive signal).

Next, the operation of the PID controller constructed as described above will be described with reference to FIG. Now, as an example of the fuzzy rule, (1) If the rate of change ΔE of the deviation E is positive and large, the operation amount is reduced. (2) If the rate of change ΔE of the deviation E is zero, the manipulated variable is maintained as it is. (3) If the rate of change ΔE of the deviation E is positive and small, increase the operation amount. And the change rate ΔE = of the deviation E between the measured value PV and the set value SV input to the PID calculation means 1.
Suppose +1 occurs.

Then, the fuzzy calculation means 2B first obtains the degree of coincidence of each rule. That is, in rule (1), since the rate of change ΔE of the deviation E is +1, the degree W is 0.6 from the membership function A1 (FIG. 4).
(See (a)). Next, in rule (2), since the rate of change ΔE of the deviation E is +1, the degree W is 0.4 from the membership function A2 (see FIG. 4B). Further, in the rule (3), the rate of change ΔE of the deviation E is +1 and therefore the degree W is 0 from the membership function A3 (see FIG. 4C).

Here, each rule (1), (2), (3)
When the degree obtained in the conclusion part is applied, the membership functions in the conclusion part become the membership functions B1, B2, B3 cut by the degree W. Next, each rule (1), (2), (3) of the conclusion part cut by the degree W
The membership functions B1, B2 and B3 of 1 are combined into one as shown in FIG. 4D, and the center of gravity of the area of the enclosed boundary portion is obtained.

Then, the obtained center of gravity is lowered vertically toward the operation amount axis (X axis), and the intersection with the operation amount axis becomes the corrected operation amount hv (= -0.5). This corrected manipulated variable hv is added to the manipulated variable mv calculated by the PID computing means 1 in the manipulated variable correction output means 3 to correct the manipulated variable mv, and then output as the final manipulated variable MV to the controlled object. To be done.

Next, FIG. 5 shows a third embodiment of the PID controller, and the same components as those in the first and second embodiments are designated by the same reference numerals. The PID control device according to this embodiment is a combination of the PID control devices of the first and second embodiments described above, and the fuzzy calculation means 2C (2) in this embodiment follows a predetermined fuzzy rule. The upper and lower limit values EU, ED of the magnitude of the deviation E are, for example, ED = -10 to EU = + 10, and the upper and lower limit values ΔEU, ΔED of the change rate ΔE of the deviation E are, for example, ΔED =-.
The correction operation amount hv is calculated from the deviation E and the change rate ΔE based on the membership function fixed to 8 to ΔEU = + 12, and the operation amount correction output means 3 calculates the correction operation amount hv from the fuzzy calculation means 2C. The final manipulated variable MV is added to the manipulated variable mv from the PID calculation means 1 and output to the controlled object.

Next, the operation of the PID controller constructed as described above will be described with reference to FIG. As an example of the fuzzy rule, (1) if the deviation E is negative and large and the rate of change ΔE of the deviation E is zero, the manipulated variable is increased by a positive value. (2) If the deviation E is zero and the rate of change ΔE of the deviation E is negative and large, the manipulated variable is increased negatively. (3) If the deviation E is positive and large and the rate of change ΔE of the deviation E is positive and large, the manipulated variable is maintained as it is. The deviation E = + 5 and the deviation E between the measured value PV and the set value SV input to the PID calculation means 1 are given.
Change rate ΔE = + 1 occurs.

Then, the fuzzy calculation means 2C obtains the degree of coincidence of each rule, the degree of the deviation E and the change rate Δ of the deviation E.
The smaller degree of the degree of E is set as the degree of the correction operation amount hv. First, in rule (1), since the deviation E is +5, the degree W is 0 from the membership function A11, and since the rate of change ΔE of the deviation E is +1, the degree W is from the membership function A12. It becomes 0.55. Since the degree of the deviation E is smaller, the degree of the correction operation amount is 0 (see FIG. 6A). Next, rule (2)
Then, since the deviation E is +5, the membership function A
21, the degree W is 0, and the change rate ΔE of the deviation E is
Is +1, the degree W is 0 from the membership function A22. Then, the deviation E and the change rate Δ of the deviation E
Since the degree of E is the same, the degree of the correction operation amount is 0 (see FIG. 6B). Further, in the rule (3), since the deviation E is +5, the degree W is 1 from the membership function A31, and since the rate of change ΔE of the deviation E is +1, the degree W is from the membership function A32. 0.
It becomes 4. Since the degree of change ΔE of the deviation E is smaller, the degree of correction operation amount is 0, 4 (FIG. 6).
(See (c)).

That is, each rule (1), (2),
When the degree obtained in the conclusion part of (3) is applied, the membership functions of the conclusion part become the membership functions B1, B2, B3 cut by the degree W. Next, each rule (1), (2) of the conclusion section cut by the degree W,
The membership functions B1, B2, B3 of (3) are combined into one, and the center of gravity of the area of the enclosed boundary portion is obtained (FIG. 6).
(See (c)).

Then, the obtained center of gravity is lowered vertically toward the operation amount axis (X axis), and the intersection with the operation amount axis becomes the corrected operation amount hv (= 0). This corrected manipulated variable hv is added to the manipulated variable mv calculated by the PID computing means 1 in the manipulated variable correction output means 3 to correct the manipulated variable mv, and then output as the final manipulated variable MV to the controlled object. To be done.

Therefore, in each of the above-mentioned first to third embodiments, the manipulated variable mv based on the result of the PID calculation by the PID calculation means 1 is calculated by the fuzzy calculation means 2 (2A, 2).
(B, 2C) can be corrected and finely adjusted by the correction operation amount hv calculated in (B, 2C). Therefore, even when the set value of the PID constant is changed, the rise time is faster than in the conventional case, and overshoot is caused for any control target. The degree of occurrence of OS or undershoot US can be reduced, and the measured value can quickly converge to the set value.

Further, when the control is stable, even if an unstable state occurs due to a disturbance, the stable state can be controlled in a short time. Further, since each parameter of the PID constant can be roughly set by the operator without being so strict, the setting time can be shortened and the work load on the operator can be reduced as compared with the conventional case.

Further, by using the fuzzy calculation means 2 which adopts the fuzzy rule, the apparatus according to the present embodiment is more effective than the conventional controller having a huge knowledge base for controlling according to the state. It is not necessary to incorporate an adjustment rule, the knowledge base can be reduced, and the overall size of the device can be reduced. Further, the PID calculation means, the fuzzy calculation means, and the manipulated variable correction output means can be further miniaturized by using a microprocessor or the like and incorporating them in a memory as software.

Next, FIG. 7 shows a fourth embodiment of the PID control device, and the same components as those in the first embodiment are designated by the same reference numerals. The PID controller according to this embodiment is
It comprises PID calculation means 1, selection means 4, first fuzzy calculation means 2D, second fuzzy calculation means 2E, third fuzzy calculation means 2F, and manipulated variable correction output means 3.

The PID calculation means 1 is the above-mentioned first to third
Similar to the embodiment, the measured values PV from a thermocouple arranged in an electric furnace and the set value SV of a preset program pattern, for example, are input as control targets, and the measured values PV and the set values are set. Deviation E from value SV (= SV-PV)
Is calculated, and the manipulated variable (e.g., the electric power for driving the heater in the electric furnace) mv based on the deviation E is output to the manipulated variable correction output means 3.

The selecting means 4 is composed of, for example, a decoder circuit or the like, and like the PID calculating means 1, the measured value PV and the set value S are set.
V is input, and based on the deviation E between the measured value PV and the set value SV, it is possible to select which of the first to third plurality of fuzzy calculation means 2D, 2E, 2F is to be used. I have decided.

The first fuzzy calculation means 2D is a selection means 4
Is selected according to a predetermined fuzzy rule, upper and lower limit values EU1 and ED1 of the deviation E are determined from the magnitude of the deviation E based on a membership function in which ED1 = -10 to EU1 = + 10, for example. The corrected manipulated variable hv is calculated and output to the manipulated variable correction output means 3.

The second fuzzy calculation means 2E is a selection means 4
When selected by, a range in which the upper and lower limit values EU2 and ED2 of the magnitude of the deviation E are smaller than the upper and lower limit values of the first fuzzy calculation means 2D, for example, ED2 = −5 to EU2 =, according to a predetermined fuzzy rule. Based on the membership function of +5, the corrected operation amount hv is calculated from the magnitude of the deviation E and is output to the operation amount correction output means 3.

The third fuzzy calculation means 2F is a selection means 4
When selected by, a range in which the upper and lower limit values EU3, ED3 of the magnitude of the deviation E are smaller than the upper and lower limit values of the second fuzzy calculation means 2E according to a predetermined fuzzy rule, for example, ED3 = -1 to EU3 = The corrected manipulated variable hv is calculated from the magnitude of the deviation E based on the membership function which is set to +1 and is output to the manipulated variable correction output means 3.

The manipulated variable correction output means 3 is composed of, for example, an adder, and the manipulated variable mv from the PID computing means 1 and any of the fuzzy computing means 2 selected by the selecting means 4.
The corrected manipulated variable hv from D (or 2E, 2F) is added to correct the manipulated variable mV, and the final manipulated variable MV corresponding to this added value is the control signal of the control target (for example, heater drive signal). Is output as. As described above, the upper and lower limit values of the deviations of the membership functions of the first to third fuzzy calculating means 2D, 2E, 2F are different and variable.

In the PID controller constructed as described above, first, when the set value SV and the measured value PV are far apart from each other, the selecting means is selected based on the magnitude of the deviation E between the set value SV and the measured value PV. 4 selects the first fuzzy computing means 2D having the largest upper and lower limits of the deviation of the membership function. As described in the operation of the first embodiment, the first fuzzy calculation means 2D calculates the correction operation amount hv based on the magnitude of the deviation E. That is, the degree W of the membership function of each rule is obtained based on the magnitude of the deviation E. Next, the obtained degree W is applied to the conclusion part of each rule to obtain the membership function of the conclusion part. Further, the obtained membership functions are combined into one, and the center of gravity of the area of the enclosed boundary portion is obtained. Then, the obtained center of gravity is vertically lowered toward the operation amount axis (X axis), and the intersection with the operation amount axis is calculated as the corrected operation amount hv.

The calculated corrected operation amount hv is input to the operation amount correction output means 3, and the operation amount correction output means 3 corrects the operation amount mv by adding the corrected operation amount hv and the operation amount mv from the operation means. Then, the final manipulated variable MV is output as a control signal for the controlled object. When the operation amount mv is corrected by the above-described operation and the set value SV and the measured value PV come close to each other and the deviation E becomes small, the first fuzzy calculation means 2D has an accuracy due to a problem such as the resolution of the membership function. Therefore, the selection means 4 selects the second fuzzy calculation means 2E in which the range of the upper and lower limits EU and ED of the deviation E of the membership function is set narrower than that of the first fuzzy calculation means 2D. The second fuzzy calculation means 2E calculates the above-mentioned correction operation amount hv, and the operation amount mv from the PID calculation means 1 is corrected by this correction operation amount hv, and the final operation amount MV is the control signal of the control target. Is output as.

Further, when the operation amount mv is corrected by the above-described operation and the measured value PV approaches the set value SV and the deviation E becomes smaller, the range of the upper and lower limit values EU and ED of the deviation E of the membership function becomes the second value. The third fuzzy calculation means 2F set to be narrower than the fuzzy calculation means 2E is selected by the selection means 4 and the correction operation amount hv is calculated in the same manner, and the correction operation amount hv is calculated from the PID calculation means 1. The manipulated variable mv is corrected and the final manipulated variable MV is output as a control signal for the controlled object.

Next, FIG. 8 shows a fifth embodiment of the PID control device. The PID control device according to this embodiment includes first to third fuzzy calculation means 2G, 2H, 2I as the fuzzy calculation means 2, and the change rate ΔE of the deviation E in each fuzzy calculation means 2G, 2H, 2I. The range of the upper and lower limit values ΔEU and ΔED is, for example, ΔED1 = −8 to ΔE.
U1 = + 12, ΔED2 = −3 to ΔEU2 = + 7, ΔE
Different from D3 = + 1 to ΔEU3 = + 3, it is variable, and the decoding circuit as the selection means 4 is based on the change rate ΔE of the deviation E between the measured value PV and the set value SV, and any fuzzy operation means 2G (or 2H, 2I) is selected, and the selected fuzzy operation means 2G (or 2H, 2I) is selected.
Change rate Δ of deviation E based on the membership function of I)
The corrected manipulated variable hv is calculated from E, and the manipulated variable correction output means 3
Is the operation amount mv from the PID calculation means 1 and the corrected operation amount hv
Is added to correct the manipulated variable mv, and the final manipulated variable MV corresponding to the added value is output as a control signal (for example, a heater drive signal) for the control target.

In the PID controller constructed as described above, the fuzzy calculation means 2 is used as in the fourth embodiment.
Of the G, 2H, 2I, the first fuzzy calculation means 2G having the largest range of the upper and lower limit values ΔEU, ΔED of the change rate ΔE of the deviation E is first selected, and the above-mentioned correction operation amount hv is calculated, The corrected operation amount hv corrects the operation amount mv from the PID calculation means 1, and the final operation amount MV is output as a control signal of the control target. Hereinafter, as the measured value PV approaches the set value SV, the second fuzzy calculation means 2
H and the third fuzzy calculation means 2I are sequentially selected by the selection means 4 and the PID is calculated by the calculated correction operation amount hv.
The manipulated variable mv from the computing means 1 is corrected and the final manipulated variable MV is output as a control signal for the controlled object.

Next, FIG. 9 shows a sixth embodiment of the PID control device. The PID control device according to this embodiment is a combination of the PID control devices of the above-described fourth and fifth embodiments. In this embodiment, the fuzzy operation means 2 has three fuzzy operations, first to third. Means 2
J, 2K, 2L, each fuzzy computing means 2J, 2
Upper and lower limit values EU and ED of deviation E in K and 2L
The range of ED = −10 to EU = + 10, ED2 =
-5 to EU2 = + 5, ED3 = -1 to EU3 = + 1, and the range of the upper and lower limit values ΔEU and ΔED of the change rate ΔE of the deviation E is, for example, ΔED1 = -8 to ΔEU1 = + 12, ΔED.
2 = −3 to ΔEU2 = + 7, ΔED3 = + 1 to ΔEU3
= + 3, which is variable, and the decoding circuit as the selection means 4 selects any fuzzy calculation means 2J (or 2K, 2L) based on the change rate ΔE of the deviation E between the measured value PV and the set value SV. Based on the membership function of the selected fuzzy calculation means 2J (or 2K, 2L), the correction operation amount hv is calculated from the deviation E and the change rate ΔE of the deviation E, and the operation amount correction output means 3 outputs the PID.
The manipulated variable mv from the calculation means 1 is added to the modified manipulated variable hv to correct the manipulated variable mV, and the final manipulated variable MV corresponding to this added value is the control signal of the control target (for example, heater drive signal). Is output as.

In the PID controller constructed as described above, the fuzzy calculation means 2 is used, as in the fourth embodiment.
Of G, 2H, 2I, the first fuzzy computing means 2J having the largest range of the upper and lower limit values EU, ED of the deviation E and the upper and lower limit values ΔEU, ΔED of the change rate ΔE of the deviation E is selected first. The above-described correction operation amount hv is calculated, the operation amount mv from the PID calculation means 1 is corrected by this correction operation amount hv, and the final operation amount MV is output as the control signal of the control target. Hereinafter, as the measured value PV approaches the set value SV, the second fuzzy calculation means 2K and the third fuzzy calculation means 2L are sequentially selected by the selection means 4, and the PID calculation means 1 is calculated by the calculated correction operation amount hv. The manipulated variable mv from is corrected and the final manipulated variable MV is output as a control signal of the controlled object.

Therefore, in each of the above-mentioned fourth to sixth embodiments, the fuzzy operation means 2D having the upper and lower limit values EU, ED, ΔEU, ΔED which are different from each other in accordance with the deviation E and the change rate ΔE of the deviation E. , 2E, 2F (fourth embodiment), 2
G, 2H, 2I (fifth embodiment), 2J, 2K, 2L (sixth embodiment) are sequentially and selectively switched to correct the manipulated variable mv, and there are a plurality of fuzzy calculation means 2D, 2
E, 2F (fourth embodiment), 2G, 2H, 2I (fifth embodiment), 2J, 2K, 2L (sixth embodiment) do not operate at the same time, and the deviation E or the change rate ΔE of the deviation E is determined. Since the configuration is such that only one unit is operated sequentially by switching the operation time, it is possible to perform highly accurate control with the calculation time being the same as the conventional one.

By the way, in the above-described sixth embodiment, the fuzzy calculation means 2J, 2K, 2L are set to the upper and lower limit values EU and ED of the magnitude of the deviation E and the upper and lower limit values ΔE of the change rate ΔE of the deviation E.
Although the configuration in which EU and ΔED are variable has been described, the upper and lower limit values EU, ED, ΔEU, and ΔED of either the magnitude of the deviation E or the change rate ΔE of the deviation E may be fixed.

Further, in each of the above-described embodiments, the case where the number of fuzzy rules is two or three has been described as an example. However, if a plurality of rules are defined, the operation amount can be corrected with higher accuracy. Further, in the case of performing finer control, it is easily realized by increasing the number of the fuzzy calculation means 2 having different upper and lower limit values EU, ED of the deviation E or upper and lower limit values ΔEU, ΔED of the change rate ΔE of the deviation E. be able to. Further, for a system in which the controlled object changes with time, stable control can be realized by devising a decoder circuit as a selecting means.

Furthermore, in each of the above-described embodiments, by changing the adjustment rule of the fuzzy calculation means 2, stable from a system having a slow control response such as temperature to a system having a fast control response such as flow rate and pressure. Can be controlled. For example, in the case of control such as a program pattern, the following fuzzy rule is added (see FIG. 10). (1A) If the previous set value change is positive and the present set value change remains, the operation amount is reduced. (2A) If the previous change in the set value is negative and the change in the current set value remains the same, increase the operation amount. (3A) If the previous set value change remains the same and the present set value change is positive, the operation amount is increased. (4A) If the previous set value change remains the same and the present set value change is negative, the operation amount is reduced.

Further, stable control can be realized even for control in which the set value changes momentarily, such as in a continuous furnace or a tunnel furnace. Further, also in the control by the cascade connection, the constant value control, etc., similarly, stable control can be performed.

[0051]

As described above, according to the PID control device of the present invention, the degree of occurrence of overshoot or undershoot is reduced for any controlled object, and the measured value is quickly converged to the set value. be able to.
Further, since the PID constant can be adjusted roughly and roughly, the burden on the operator can be reduced, the adjustment time can be shortened, and the calculation time can be shortened and stable control can be performed. Further, according to the PID control device of claim 2, only one of the plurality of fuzzy calculation means is selected in accordance with the deviation E or the change rate ΔE of the deviation E, and the fuzzy calculation means are sequentially operated. High-precision control can be performed without changing.

[Brief description of drawings]

FIG. 1 is a block configuration diagram showing a first embodiment of a PID control device according to the present invention.

FIG. 2 is a diagram for explaining the operation of fuzzy control means based on fuzzy rules in the first embodiment of the same device.

FIG. 3 is a block configuration diagram showing a second embodiment of the PID control device according to the present invention.

FIG. 4 is a diagram for explaining the operation of fuzzy control means based on fuzzy rules in the second embodiment of the same device.

FIG. 5 is a block diagram showing the third embodiment of the PID control device according to the present invention.

FIG. 6 is a diagram for explaining the operation of fuzzy control means based on fuzzy rules in the third embodiment of the device.

FIG. 7 is a block diagram showing a fourth embodiment of the PID control device according to the present invention.

FIG. 8 is a block configuration diagram showing a fifth embodiment of the PID control device according to the present invention.

FIG. 9 is a block diagram showing the sixth embodiment of the PID control device according to the present invention.

FIG. 10 is a diagram showing an example of transition of a control amount with respect to a temperature program pattern controlled by a controller.

[Explanation of symbols]

1 ... PID computing means, 2 (2A to 2L) ... fuzzy computing means, 3 ... manipulation amount correction output means, 4 ... selecting means, SV ...
Set value, PV ... Measured value, E ... Deviation, ΔE ... Change rate, mv
... manipulated variable, hv ... modified manipulated variable, MV ... final manipulated variable.

Claims (2)

[Claims] 1. A PID control device that calculates a deviation between a preset set value and a measured value from a controlled object and outputs a manipulated variable corresponding to the PID calculated value. According to a fuzzy rule, the magnitude of the deviation of the measured value from the controlled object or the rate of change of the deviation based on a membership function in which the upper and lower limit values of at least one of the magnitude of the deviation and the rate of change of the deviation are fixed Based on the correction operation amount calculated by the fuzzy calculation means and the fuzzy calculation means for calculating the correction operation amount from
A PID control device comprising: a manipulated variable correction output unit that corrects a value calculated by ID and outputs a manipulated variable. 2. A PID control device that calculates a deviation between a preset set value and a measured value from a controlled object, and outputs a manipulated variable corresponding to the PID calculated value. The magnitude of the deviation of the measured value from the controlled object or the rate of change of the deviation based on a membership function in which the upper and lower limit values of at least one of the magnitude of the deviation and the rate of change of the deviation are variable according to a fuzzy rule. A fuzzy computing means for computing a correction operation amount, a selecting means for sequentially switching and selecting the fuzzy computing means according to the magnitude of the deviation or the rate of change of the deviation, and the fuzzy computing means selected by the selecting means. And a manipulated variable correction output means for correcting the value calculated by the PID based on the corrected manipulated variable calculated by the above and outputting the manipulated variable. D controller.